1. Field of the Invention
This invention relates to an apparatus and a method used in text message communications such as SMS (Short Message Service) messages, and more particularly to the selection of coding data sets for use in transmission of messages in such an apparatus and a method.
2. Description of the Related Arts
Short message service transmissions have become increasingly popular over the last few years as the use of mobile telephones and other handheld devices has increased. Short message service transmissions can now also be made from other portable devices, from telephones connected to landlines, and from personal computers. It is expected that their use will continue to increase.
An SMS message is typically input to a terminal device such as a cellular phone by a user using the keypad of that device. Once the message has been input, a recipient is selected and the message is transmitted from the device to the recipient via one or more communication networks.
There are a number of communication formats known as alphabets or coding data sets which are used for transmission. These alphabets are used for coding the characters used in a message to be transmitted. The most basic of these alphabets is the GSM (Global System for Mobile communication) 7-bit default alphabet. This is capable of supporting a total of 256 different characters, thus it has sufficient characters for the standard 26-bit English alphabet, numerals 0 to 9, and various foreign language special characters and characters with accents.
A more sophisticated alphabet for transmission is an 8-bit alphabet which allows a total of 512 different characters to be transmitted. Beyond this, there is now available the UCS2 16-bit alphabet which permits a total 131,072 different characters to be transmitted.
In most countries a number of different networks support SMS messaging using one or more of the available alphabet sets. Where a messaging terminal device is supplied by a network provider it is usual for that device to support the SMS alphabet of that provider, however, as people travel more frequently, mobile devices are required to operate across a plurality of different networks. This can result in SMS messaging not being available to users when their devices are connected to certain networks.